Bluetooth™ and Wi-Fi™ are commonly used wireless data transmission protocols. Wi-Fi and Bluetooth both occupy a section of the 2.4 GHz Industrial, Scientific, and Medical (“ISM”) band that is 83 MHz-wide. Bluetooth is an industrial specification that can be used for wireless personal area networks. Bluetooth can be used to connect and exchange information between devices such as mobile phones, laptops, personal computers, hand-held computers, printers, digital cameras, and video game consoles. Bluetooth can be particularly useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Common applications of Bluetooth can include wireless control of and communication between a mobile phone and a hands-free headset (e.g., a Bluetooth ear bud), wireless networking between computers for certain applications, and wireless communications between a computer and input and output devices (e.g., mice, keyboards, and printers). Bluetooth uses Frequency Hopping Spread Spectrum (FHSS) and is allowed to hop between 79 different 1 MHz-wide channels in the ISM band.
“Wi-Fi” refers to wireless technology based upon the IEEE 802.11 standards generally used for wireless local area networking (WLAN). Common applications for Wi-Fi include internet access and network connectivity for consumer electronics such as televisions, DVD players, and digital cameras. Wi-Fi generally uses the same radio frequencies as Bluetooth, but operates using higher power, generally resulting in a stronger connection that can cover a greater distance. Because both Wi-Fi and Bluetooth wireless technology share the spectrum and can often be located in close physical proximity to one another,
Time Division Multiplexing (TDM) is a coexistence method where Bluetooth and Wi-Fi take turns transmitting. In TDM, two or more signals or bit streams are transferred appearing simultaneously as sub-channels in one communication channel, but are physically taking turns on the channel. The time domain is divided into several recurrent time slots of fixed length, one for each sub-channel.
Using TDM in Wi-Fi and Bluetooth coexistence system, Bluetooth is not allowed to transmit or receive data packets in Wi-Fi time slots. When more than one Bluetooth links are established with different devices, as long as one of Bluetooth links operates in TDM the other Bluetooth links have to use TDM as well. All Bluetooth links transmit and receive data packets only in Bluetooth time slots, which cause inefficiency in Bluetooth data transmission.